This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-273819 filed Sep. 8, 2000.
The present invention relates to an in-vehicle key check system, which checks an electronic key in a vehicle by communication with the electronic key carried by a user.
Some vehicles have electronic key systems, so that vehicle doors are opened and closed automatically by communication between a portable transponder (electronic key) carried by a vehicle user and an electronic control unit installed in a vehicle (in-vehicle ECU). In these systems, the in-vehicle ECU transmits a wireless request signal toward a vehicle outside and the electronic key transmits a wireless response signal including its identification information stored therein, while the vehicle user with the electronic key is outside the vehicle within a specified area of the vehicle. The in-vehicle ECU checks the identification code in the response signal to enable and disable automatic door control based on the check result.
Other vehicles have different electronic key systems, so that a vehicle steering or a vehicle engine is rendered operative by communication between an electronic key and an in-vehicle ECU. In these systems, communication between the in-vehicle ECU and the electronic key is limited within an in-vehicle area, that is, within a vehicle compartment. The in-vehicle ECU also checks whether the electronic key is an authorized one to allow the steering operation or the engine operation.
In the in-vehicle key check operation, the electronic key transmits various identification codes, random numbers and the like in a plurality of time stages for an improved security. This operation requires several hundred milliseconds (ms) to complete one cycle. This operation is performed for each of various predetermined check conditions, thus increasing the check operation time. Thus, the steering or engine operation is disabled for a certain time immediately after a vehicle user gets into a vehicle.
It is therefore an object of the present invention to reduce in-vehicle key check operation time and processing of an in-vehicle electronic control unit.
According to the present invention, an in-vehicle check system for a vehicle comprises a transmitter, a receiver and an electronic unit installed in a vehicle for communication with a portable transponder carried by a user. The electronic unit checks whether the portable transponder is an authorized one based on wireless communication with the transponder in the vehicle. The electronic unit includes a memory for storing a check result indicating that the portable transponder is the authorized one, and checks the memory for the check result and eliminates another check operation when the check result is stored in the memory.
Preferably, the electronic unit communicates with the portable transponder through the wireless signals in a plurality of time-divided stages to complete one cycle of its checking operation. The electronic unit checks the memory for the check result each time a predetermined in-vehicle check condition is satisfied. The electronic unit erases the check result stored in the memory, when a predetermined condition indicating a possibility of taking out the portable transponder from the vehicle is detected or when a predetermined time elapses after the check result is stored in the memory.